Authorities have never revealed that the case against the man who some believe was the biggest drug kingpin in the world began with Baines, a mid-level dealer whose father owned a grocery store in Austin and also drove a bus for the CTA.

But a Sun-Times review of court records and interviews with Baines and others involved in the case, including a key former federal prosecutor, has found that a Drug Enforcement Administration task force used a web of informants and hundreds of wiretapped calls to trace a path that ultimately led from Baines to El Chapo.

“We went from the streets of Chicago to the mountaintops of Mexico,” says Thomas Shakeshaft, a former assistant U.S. attorney who supervised each phase of the investigation. “We started a case against the Traveling Vice Lords on the West Side of Chicago and went all the way up.

“Before Sean Penn flew down to Mexico with [actress] Kate del Castillo and recorded this thing where Chapo admitted he was the largest drug-trafficker in the world, we had the only legally admissible voice recording of Chapo in the world.”

The twins agreed to cooperate with U.S. investigators in late 2008, court records show, and Pedro Flores recorded a damning phone conversation with his supplier — El Chapo. The recording became the key evidence in the 2009 federal indictment filed in U.S. District Court in Chicago.